/* A commutator that processes a single token per iteration.
Copyright (c) 2002-2009 The Regents of the University of California.
All rights reserved.
Permission is hereby granted, without written agreement and without
license or royalty fees, to use, copy, modify, and distribute this
software and its documentation for any purpose, provided that the above
copyright notice and the following two paragraphs appear in all copies
of this software.
IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
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THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF
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ENHANCEMENTS, OR MODIFICATIONS.
PT_COPYRIGHT_VERSION_2
COPYRIGHTENDKEY
*/
package ptolemy.actor.lib;
import ptolemy.kernel.CompositeEntity;
import ptolemy.kernel.util.IllegalActionException;
import ptolemy.kernel.util.NameDuplicationException;
//////////////////////////////////////////////////////////////////////////
//// SingleTokenCommutator
/**
The SingleTokenCommutator has a multiport input port and an output
port. The types of the ports are undeclared and will be resolved by
the type resolution mechanism, with the constraint that the output
type must be greater than or equal to the input type. On each call to
the fire method, the actor reads one token from the current input,
and writes one token to an output channel. If there is no token on
the input, then it will not produce a token on the output. In the
next iteration of this actor, it will read the next channel.
@author Paul Whitaker, Mudit Goel, Edward A. Lee, Christopher Hylands, Jim Armstrong
@version $Id$
@since Ptolemy II 2.0
@Pt.ProposedRating Yellow (cxh)
@Pt.AcceptedRating Yellow (cxh)
*/
public class SingleTokenCommutator extends Transformer implements SequenceActor {
// SingleTokenCommutator used to be in sr.lib, but
// ddf.lib.DDFSingleTokenCommutator depends on it, so we moved it
// to actor.lib
/** Construct an actor in the specified container with the specified
* name. Create ports and make the input port a multiport. Create
* the actor parameters.
*
* @param container The container.
* @param name This is the name of this distributor within the container.
* @exception NameDuplicationException If an actor
* with an identical name already exists in the container.
* @exception IllegalActionException If the actor cannot be contained
* by the proposed container.
*/
public SingleTokenCommutator(CompositeEntity container, String name)
throws NameDuplicationException, IllegalActionException {
super(container, name);
input.setMultiport(true);
}
///////////////////////////////////////////////////////////////////
//// public methods ////
/** Read at most one token from the current input channel and write that
* token to the output channel. If there is no token on the current
* input channel, do nothing.
* @exception IllegalActionException If there is no director.
*/
public void fire() throws IllegalActionException {
super.fire();
if (input.hasToken(_currentInputPosition)) {
output.send(0, input.get(_currentInputPosition));
}
}
/** Begin execution by setting the current input channel to zero.
* @exception IllegalActionException If there is no director.
*/
public void initialize() throws IllegalActionException {
super.initialize();
_currentInputPosition = 0;
}
/** Update the input position to equal that determined by the most
* recent invocation of the fire() method. The input position is
* the channel number of the input port from which the next input
* will be read.
* @exception IllegalActionException If there is no director.
*/
public boolean postfire() throws IllegalActionException {
_currentInputPosition++;
if (_currentInputPosition >= input.getWidth()) {
_currentInputPosition = 0;
}
return super.postfire();
}
///////////////////////////////////////////////////////////////////
//// protected methods ////
/** Get the current input position.
* @return Current input position.
*/
// This method is Added by Gang Zhou so that DDFSingleTokenCommutator
// can inherit this class.
protected int _getCurrentInputPosition() {
return _currentInputPosition;
}
///////////////////////////////////////////////////////////////////
//// private variables ////
// The channel number for the next input.
private int _currentInputPosition;
}